A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

              [Sort alphabetically]   [Restore default list]

  Subjects -> METEOROLOGY (Total: 106 journals)
Showing 1 - 36 of 36 Journals sorted by number of followers
Nature Climate Change     Full-text available via subscription   (Followers: 147)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 143)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 83)
Atmospheric Research     Hybrid Journal   (Followers: 73)
Atmospheric Environment     Hybrid Journal   (Followers: 72)
Climatic Change     Open Access   (Followers: 69)
Bulletin of the American Meteorological Society     Open Access   (Followers: 63)
Advances in Climate Change Research     Open Access   (Followers: 57)
Journal of Climate     Hybrid Journal   (Followers: 56)
Climate Policy     Hybrid Journal   (Followers: 51)
Climate Change Economics     Hybrid Journal   (Followers: 48)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 45)
Climate Dynamics     Hybrid Journal   (Followers: 45)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 43)
Weather and Forecasting     Hybrid Journal   (Followers: 43)
Journal of Applied Meteorology and Climatology     Hybrid Journal   (Followers: 42)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 40)
Atmospheric Science Letters     Open Access   (Followers: 40)
Journal of Hydrology and Meteorology     Open Access   (Followers: 39)
American Journal of Climate Change     Open Access   (Followers: 38)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 33)
Atmosphere     Open Access   (Followers: 33)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 32)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 32)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 31)
Journal of Space Weather and Space Climate     Open Access   (Followers: 31)
Monthly Weather Review     Hybrid Journal   (Followers: 30)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 30)
International Journal of Climatology     Hybrid Journal   (Followers: 28)
Space Weather     Full-text available via subscription   (Followers: 28)
Advances in Meteorology     Open Access   (Followers: 27)
Journal of Climate Change     Full-text available via subscription   (Followers: 25)
Energy & Environment     Hybrid Journal   (Followers: 25)
International Journal of Atmospheric Sciences     Open Access   (Followers: 25)
Climate Change Responses     Open Access   (Followers: 24)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 23)
Environmental Dynamics and Global Climate Change     Open Access   (Followers: 22)
International Journal of Environment and Climate Change     Open Access   (Followers: 22)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 21)
Climate Resilience and Sustainability     Open Access   (Followers: 21)
Current Climate Change Reports     Hybrid Journal   (Followers: 21)
Tellus A     Open Access   (Followers: 21)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 21)
Journal of Economic Literature     Hybrid Journal   (Followers: 20)
Tellus B     Open Access   (Followers: 20)
Global Meteorology     Open Access   (Followers: 20)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 19)
Weatherwise     Hybrid Journal   (Followers: 18)
Weather and Climate Extremes     Open Access   (Followers: 18)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 16)
Economics of Disasters and Climate Change     Hybrid Journal   (Followers: 16)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 15)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 14)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 14)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 13)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 12)
Climate Risk Management     Open Access   (Followers: 10)
Journal of Hydrometeorology     Hybrid Journal   (Followers: 10)
Climate Research     Hybrid Journal   (Followers: 9)
Climate     Open Access   (Followers: 8)
The Cryosphere (TC)     Open Access   (Followers: 8)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 7)
Climate and Energy     Full-text available via subscription   (Followers: 7)
Aeolian Research     Hybrid Journal   (Followers: 7)
Climate of the Past (CP)     Open Access   (Followers: 7)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 6)
npj Climate and Atmospheric Science     Open Access   (Followers: 6)
Open Atmospheric Science Journal     Open Access   (Followers: 6)
Journal of Climate Change and Health     Open Access   (Followers: 6)
Carbon Balance and Management     Open Access   (Followers: 6)
Climate Law     Hybrid Journal   (Followers: 6)
Urban Climate     Hybrid Journal   (Followers: 5)
Open Journal of Modern Hydrology     Open Access   (Followers: 5)
Bulletin of Atmospheric Science and Technology     Hybrid Journal   (Followers: 5)
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 4)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 4)
Journal of Weather Modification     Full-text available via subscription   (Followers: 4)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 4)
Journal of Climatology     Open Access   (Followers: 4)
Meteorological Applications     Open Access   (Followers: 4)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Climate Services     Open Access   (Followers: 4)
Frontiers in Climate     Open Access   (Followers: 4)
Environmental and Climate Technologies     Open Access   (Followers: 3)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 3)
Atmospheric Environment : X     Open Access   (Followers: 3)
International Journal of Biometeorology     Hybrid Journal   (Followers: 3)
Journal of Meteorological Research     Full-text available via subscription   (Followers: 2)
GeoHazards     Open Access   (Followers: 2)
气候与环境研究     Full-text available via subscription   (Followers: 2)
Atmósfera     Open Access   (Followers: 2)
Mediterranean Marine Science     Open Access   (Followers: 2)
Meteorologica     Open Access   (Followers: 2)
Studia Geophysica et Geodaetica     Hybrid Journal   (Followers: 1)
Weather and Climate Dynamics     Open Access   (Followers: 1)
Modeling Earth Systems and Environment     Hybrid Journal   (Followers: 1)
Nīvār     Open Access   (Followers: 1)
Climate of the Past Discussions (CPD)     Open Access   (Followers: 1)
Tropical Cyclone Research and Review     Open Access   (Followers: 1)
Ciencia, Ambiente y Clima     Open Access   (Followers: 1)
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access   (Followers: 1)
Earth Perspectives - Transdisciplinarity Enabled     Open Access   (Followers: 1)
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Meteorological Monographs     Hybrid Journal   (Followers: 1)
Journal of Agricultural Meteorology     Open Access  
Mètode Science Studies Journal : Annual Review     Open Access  

              [Sort alphabetically]   [Restore default list]

Similar Journals
Journal Cover
Studia Geophysica et Geodaetica
Journal Prestige (SJR): 0.38
Citation Impact (citeScore): 1
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-1626 - ISSN (Online) 0039-3169
Published by Springer-Verlag Homepage  [2469 journals]
  • Velocity analysis of noisy seismic data based on RSVD weighted semblance

    • Free pre-print version: Loading...

      Abstract: Abstract The accuracy of velocity spectrum affects the subsequent processing of seismic data. Though the singular value decomposition (SVD) weighted semblance has a higher velocity resolution than conventional semblance, its performance is degraded for noisy seismic data. A rectified SVD weighted semblance method (RSVD), aiming to improve the accuracy of velocity spectrum for seismic data contaminated by noise, is proposed. In this approach, the weighting function is constructed from the first two singular values and their mean square error obtained via SVD of noisy seismic data after normal moveout (NMO) with scanning velocity. Synthetic and field examples demonstrate that the proposed method performs better than the SVD weighted semblance in enhancing the accuracy of velocity spectra for noisy near-offset common midpoint gathers in layered isotropic media.
      PubDate: 2022-04-30
       
  • Erratum to “Improving the accuracy of the expanded anisotropic eikonal
           equation at larger offsets using Levin’s T-transformation”

    • Free pre-print version: Loading...

      PubDate: 2022-04-04
       
  • Expressions for the calculation of isotropic Gaussian filter kernels in
           the spherical harmonic domain

    • Free pre-print version: Loading...

      Abstract: Abstract The isotropic Gaussian filter has been used extensively in Gravity Recovery and Climate Experiment (GRACE) temporal gravity field solutions, and is still being applied to GRACE Follow-On products to remove high-frequency errors and improve the estimation of mass transport events on the Earth’s surface. For such applications, the only known rigorous method to calculate the spherical harmonic coefficients of an isotropic Gaussian filter is by the use of a second-order recurrence relation. As an alternative, an approximate expression is also used frequently. In this paper, we provide some additional expressions for the calculation of isotropic Gaussian filter kernels in the spherical harmonic domain. Specifically, we derive a new recurrence relation, a closed-form expression, expressions involving modified Bessel functions of the first kind, and a new approximate expression. We also examine and compare them from a computational viewpoint. The results of our numerical investigations indicate that the new recurrence relation and the closed-form expression are unstable in a way similar to the second-order recurrence relation that has been used so far. The expressions involving modified Bessel functions, and particularly the ones using exponentially scaled modified Bessel functions, provide a simple, elegant and stable way of calculating isotropic Gaussian filter coefficients, since routines for their stable evaluation are readily available in many programming languages. Alternatively, the new approximate expression can be used, which is also stable and offers better accuracy than previous approximations.
      PubDate: 2022-04-04
      DOI: 10.1007/s11200-021-0272-9
       
  • Evaluation of latest marine gravity field models derived from satellite
           altimetry over the Gulf of Guinea (Central Africa) with shipborne gravity
           data

    • Free pre-print version: Loading...

      Abstract: Abstract The marine gravity field is vital for mapping various submarine geological and tectonic structures, also for computation of high-resolution gravimetric geoid. This study aims to evaluate the accuracy of two latest high-resolution marine gravity models derived from satellite altimetry (DTU17 and SSv27.1) using shipborne gravity data and to pruduce high-precision gravity field over the Gulf of Guinea. The gross-errors affecting the shipborne gravity data have been removed by cross-validation technique to ensure better evaluation of gravity field models. The standard deviation σ of the differences between the measured and model gravity data drops from 9.96 mGal before the cross-validation to 6.28 mGal after this process. The comparison between the DTU17 and SSv27.1 gravity field models has been done in order to detect significant differences between them. The differences between the two models are quite small with a mean of 1.73 mGal and σ of 6.55 mGal. The discrepancies between them are found around coastal areas and along islands. This shows the poor accuracy of satellite altimetry near coastal areas. Afterwards, the accuracy of each marine gravity field models was evaluated using shipborne gravity data free of gross-errors. The SSv27.1 model fits better to the shipborne gravity data with a mean of −4.88 mGal and σ of 7.18 mGal. Hence, the SSv27.1 model has a better performance than the DTU17 model on the Gulf of Guinea. Finally, we used the least-squares collocation technique associated to the Markov model of second-order covariance to combine the SSv27.1 model with the shipborne gravity data. We produced here a marine gravity field of good accuracy around the Gulf of Guinea with no data gaps. The precision of this combined gravity field is estimated to be 5.54 mGal with a spatial resolution of 1 arc-minute.
      PubDate: 2022-04-04
      DOI: 10.1007/s11200-021-0157-y
       
  • Rotationally invariant viscoelastic medium with a non-symmetric stiffness
           matrix

    • Free pre-print version: Loading...

      Abstract: Abstract The stiffness matrix of a viscoelastic medium is symmetric in the low—frequency and high—frequency limits, but not for finite frequencies. We thus consider a non—symmetric stiffness matrix in this paper. We determine the general form of a rotationally invariant non—symmetric stiffness matrix of a viscoelastic medium. It is described by three additional complex—valued parameters in comparison with a rotationally invariant symmetric stiffness matrix of a transversely isotropic (uniaxial) viscoelastic medium with a symmetric stiffness matrix. As a consequence, we find that the stiffness matrix of an isotropic viscoelastic medium is always symmetric.
      PubDate: 2022-02-08
      DOI: 10.1007/s11200-021-1106-5
       
  • Geoelectrical imaging and spatial distribution of alluvial materials of
           the Sanaga River (Cameroon, Central Africa)

    • Free pre-print version: Loading...

      Abstract: Abstract Recent research has shown that the floodplains of the Sanaga river catchment contain significant resources of minerals suitable for industry. However, these studies were carried out in large grids, and do not allow for detailed specification of the geometry of the identified resources. The aim of this study is to minimize the uncertainties observed in the characterization of these deposits using two techniques: geoelectric imaging and manual drilling. The geoelectrical results associated with the lithological sections show, from surface to depth, three main units: semi-resistive (66–500 Ωm) corresponding to clayey sands; conductive (42–100 Ωm) associated with sandy clays/silt clays, and resistive (<1000 Ωm) corresponding to sands and gravels. The data show good correlation between resistivity and clay content, and resistivity and sand content. Similarly, good correlation exists between the thickness determined by geoelectrical method and the actual thickness. The average thickness of these layers on the banks of the Sanaga river, suitable for exploitation, is 4 m over an area of about 100 m2. Our results show that the combination of geoelectric technique and manual drilling allows a good assessment of the volume of deposits of useful resources and can better constrain their exploitation in the field of civil engineering.
      PubDate: 2022-02-08
      DOI: 10.1007/s11200-020-1083-0
       
  • Application of the nonlinear optimisation in regional gravity field
           modelling using spherical radial base functions

    • Free pre-print version: Loading...

      Abstract: Abstract The gravity field is a signature of the mass distribution and interior structure of the Earth, in addition to all its geodetic applications especially geoid determination and vertical datum unification. Determination of a regional gravity field model is an important subject and needs to be investigated and developed. Here, the spherical radial basis functions (SBFs) are applied in two scenarios for this purpose: interpolating the gravity anomalies and solving the fundamental equation of physical geodesy for geoid or disturbing potential determination, which has the possibility of being verified by the Global Navigation Satellite Systems (GNSS)/levelling data. Proper selections of the number of SBFs and optimal location of the applied SBFs are important factors to increase the accuracy of estimation. In this study, the gravity anomaly interpolation based on the SBFs is performed by Gauss-Newton optimisation with truncated singular value decomposition, and a Quasi-Newton method based on line search to solve the minimisation problems with a small number of iterations is developed. In order to solve the fundamental equation of physical geodesy by the SBFs, the truncated Newton optimisation is applied as the Hessian matrix of the objective function is not always positive definite. These two scenarios are applied on the terrestrial free-air gravity anomalies over the topographically rough area of Auvergne. The obtained accuracy for the interpolated gravity anomaly model is 1.7 mGal with the number of point-masses about 30% of the number of observations, and 1.5 mGal in the second scenario where the number of used kernels is also 30%. These accuracies are root mean square errors (RMSE) of the differences between predicted and observed gravity anomalies at check points. Moreover, utilising the optimal constructed model from the second scenario, the RMSE of 9 cm is achieved for the differences between the gravimetric height anomalies derived from the model and the geometric height anomalies from GNSS/levelling points.
      PubDate: 2021-12-12
      DOI: 10.1007/s11200-020-1077-y
       
  • Velocity structure and its relation to the seismicity of Datong Window and
           adjacent regions in Shanxi Province, North China

    • Free pre-print version: Loading...

      Abstract: Abstract Datong Window is at the junction of Datong Basin and Liulengshan Range in the northern part of Shanxi Graben, China. It is important to analyze the relationship between the frequency of small earthquakes and the deep velocity structure in this region since the earthquake swarm in 1989 with the maximum surface-wave magnitude Ms of 5.9. A high-resolution 3D P-wave velocity model of the crust in this region was obtained with double-difference tomography using seismic data from July 2009 to June 2019. The results show that the Datong-Yanggao seismic sequence occurred, in general, within the NE rupture zone of the earthquake swarm of 1989. The sequences from 1991, 1999, and 2010 were in the rupture zone of 1989. A series of earthquakes developed in this region, which is at the intersection of multiple faults and a low-velocity anomaly of the intermediate-lower crust. A gap of length of about 3 km was found at the southwest end of the NE Dawangcun Fault (near Lujialing). Several moderate earthquake ruptures failed to break through it. It was speculated that it may be a potential asperity. There is a possibility of an earthquake with magnitude about 5 from the gap. The relocation results for the earthquakes show that intensive small-earthquake events in Datong Window corresponding to moderate-to-strong earthquakes in Shanxi Graben were highly clustered horizontally and distributed vertically in a column. In contrast, when there was no moderate earthquake in Shanxi Graben after intensive small-earthquake events, the spatial distribution of these events in Datong Window was scattered and dispersive.
      PubDate: 2021-12-12
      DOI: 10.1007/s11200-021-1026-4
       
  • Two S-wave eigenvectors of the Christoffel matrix need not exist in
           anisotropic viscoelastic media

    • Free pre-print version: Loading...

      Abstract: Abstract The 3×3×3×3 frequency-domain stiffness tensor is complex-valued in viscoelastic media. The 3 × 3 Christoffel matrix is then also complex-valued. Using a simple example, we demonstrate that a complex-valued Christoffel matrix need not have all three eigenvectors at an S-wave singularity, and we thus cannot apply the eigenvectors to calculating the phase-space derivatives of the Hamiltonian function.
      PubDate: 2021-11-15
      DOI: 10.1007/s11200-021-0824-z
       
  • Sensitivity Gaussian packets

    • Free pre-print version: Loading...

      Abstract: Abstract Perturbations of elastic moduli and density can be decomposed into Gabor functions. The wave field scattered by the perturbations is then composed of waves scattered by the individual Gabor functions. The scattered waves can be estimated using the first-order Born approximation with the paraxial ray approximation. For a particular source generating a short-duration broad-band incident wave field with a smooth frequency spectrum, each Gabor function generates at most a few scattered sensitivity Gaussian packets propagating in determined directions. Each of these scattered Gaussian packets is sensitive to just a single linear combination of the perturbations of elastic moduli and density corresponding to the Gabor function. This information about the Gabor function is lost if the scattered sensitivity Gaussian packet does not fall into the aperture covered by the receivers and into the recording frequency band. We illustrate this loss of information using the difference between the 2-D Marmousi model and the corresponding smooth velocity model. We decompose the difference into Gabor functions. For each of the 240 point shots, we consider 96 receivers. For each shot and each Gabor function, we trace the central ray of each sensitivity Gaussian packet. If a sensitivity Gaussian packet arrives to the receiver array within the recording time interval and frequency band, the recorded wave field contains information on the corresponding Gabor function. We then decompose the difference into the part influencing some recorded seismograms, and the part on which we recorded no information and which thus cannot be recovered from the reflection experiment.
      PubDate: 2021-11-15
      DOI: 10.1007/s11200-021-0931-x
       
  • Error bounds for the spectral approximation of the potential of a
           homogeneous almost spherical body

    • Free pre-print version: Loading...

      Abstract: Abstract Several kinds of approximation of the gravitational potential of a homogeneous body by truncated spherical harmonics series are in use in physical geodesy. However, only one of them is capable of a representation converging to the true potential in the whole layer between the Brillouin sphere and the Bjerhammar sphere of the body. We aim at providing various majorizations, namely upper bounds, of the error with the double purpose of proving explicitly the convergence in the sense of different norms and of giving computable bounds, that might be used in numerical studies. The first aim is reached for all the norms. For the second, however, it turns out that among the bounds, when applied to the example of the terrain correction of the Earth, only those referring to the mean absolute error and the mean squared error at the level of Brillouin sphere of minimum radius give significant and useful results. In order to make the computation an easy exercise, a simple approximate formula has been developed requiring only the use of the distribution function of the heights of the surface of the body with respect to the Bjerhammar sphere.
      PubDate: 2021-09-04
      DOI: 10.1007/s11200-021-0730-4
       
  • The stability criterion for downward continuation of surface gravity data
           with various spatial resolutions over Ireland

    • Free pre-print version: Loading...

      Abstract: Abstract The differences between local and reference geopotential values are the fundamental quantities of interest in the geodetic boundary value problem approach for connecting independent height reference frames. The local gravity potential values are usually derived from gravimetric and geometric geoid undulations. In determining the short-wavelength components of the gravimetric geoid, a harmonic or analytical downward continuation of the external harmonic functions of gravity to the geoid is necessary. This study analyses the stability of the Poisson downward continuation technique with respect to varying the spatial resolution of surface gravity data in Ireland in order to estimate an effective grid resolution on this reduction. Results of the study show that the minimum range of 500-m resolution provides an unconditionally stable solution to downward continuation without the need for regularisation of the computation algorithm. In this case, downward continued data contribute from −13 to 12 mm to geoid heights and from −0.128 to 0.118 m2s−2 to local gravity potential value at Malin-Head tide gauge station in Ireland.
      PubDate: 2021-09-04
      DOI: 10.1007/s11200-020-0769-7
       
  • Erratum to “Bounds and averages of seismic quality factor Q”

    • Free pre-print version: Loading...

      PubDate: 2021-07-28
      DOI: 10.1007/s11200-021-0428-7
       
  • Relationship between soil magnetic susceptibility enhancement and
           precipitation in Cretaceous paleosols

    • Free pre-print version: Loading...

      Abstract: Abstract Magnetic susceptibility (MS) is widely used for paleoclimate reconstruction. In one of the previous studies, data from 12 locations of modern middle- and low-latitude soils revealed that MS increases with increasing precipitation from approximately 200 to 1000–1200 mm yr−1 and then decreases with further precipitation. However, as a result of diverse sediment sources from different locations, the MS value can deviate, affecting its relationship with the climate. Sediments of a section experience dry-wet contrast due to the migration of climate zones as a function of geological time, and form different soil types with various colors. If the sediments of a section have the same source material, different soil types in that section would enable us to explore the relationship between MS enhancement and precipitation using paleosols and to verify the previous results. Herein, we investigated Cretaceous variegated sediments in the Zhonggou and Xiagou Formations located in the Hexi Corridor of China. The rare earth and trace element analyses reveal that these sediments have the same source area. Environmental magnetism and geochemical methods reveal that the sedimentary environment of the yellowish-brown, red, and grayish-white sediments ranges from dry to wet. Precipitation reconstruction for the paleosols with a climate transfer function shows that MS increases with increasing precipitation up to approximately 800 ± 182 mm yr−1 and decreases with higher precipitation amounts. The changing pattern of MS is consistent with the previous results, but the inflection point in the MS vs. precipitation curve appears at slightly lower precipitation value. Thus, paleosol sequences are suited for the analysis of paleoprecipitation trends with the help of MS.
      PubDate: 2021-07-28
      DOI: 10.1007/s11200-020-0576-1
       
  • Velocity structure of the upper crust beneath the Jiaonan uplift and its
           adjacent areas, China

    • Free pre-print version: Loading...

      Abstract: Abstract The Jiaonan uplift and its adjacent areas (JUAA) are the result of collision and amalgamation of the North China plate and Yangtze plate. In this area, the tectonic environment is complex and crustal deformation is strong. However, detailed and in-depth study of the upper crustal structure and medium properties in the JUAA has not previously been performed. The high-resolution three-dimensional crustal velocity structure of the JUAA is helpful to analyze the characteristics of the crustal structure in this area and is important for evaluating the tectonic environment and medium properties of the JUAA. We obtained the three-dimensional crustal velocity structure in the JUAA using the double-difference seismic tomography technique, and found that the Rizhao area and the sea areas to its southwest in the Jiaonan uplift are characterized by a high-velocity structure, and that most of the high-velocity anomaly area is located in the sea area. The crustal velocity values of the southern end of the Yishu fault zone are also high. The high crustal velocity anomaly areas in the JUAA are considered to be caused by the upwelling of mantle material. The velocity structure of the upper crust beneath the depression structures shows notable low-velocity anomalies, which are closely related to loose sediments in the depression structures. The existence of abnormally high-velocity and low-velocity structures in the Jiaonan uplift indicates that there are substantial differences in the properties of the crustal media in the Jiaonan uplift. Crust-mantle interaction in the Jiaonan uplift is mainly concentrated in the Rizhao area and sea areas to its southwest.
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-020-0164-4
       
  • Assessment of state of earth dam of Elchovka settling pond by combination
           of electromagnetic soundings and polarization methods

    • Free pre-print version: Loading...

      Abstract: Abstract Earth dams are constantly under the hydraulic pressure. Their long-term operation leads to arising of zones of increased water cut and filtration in body and base of dams. This weakens dam’s strength. Geophysical methods can be used to control condition of the soil structures. We describe the research results of the Elchovka earth dam by a complex of electrometric methods, as they are most sensitive to changes in soil moisture. We applied the self-potential (SP) method, the vertical electrical soundings (VES) and the remote induction soundings (RIS) with the study of the frequency dispersion of electrical resistivity. Main pathways of the water filtration were identified by the self-potential method. According to the results of RIS, the boundary between bulk and natural soils as well as the boundary between sedimentary and bedrock are clearly distinguished. Electric soundings on direct current (VES) allowed us to localize places with reduced resistivities due to increased soil moisture. Frequency dispersion anomalies, which can also indicate water filtration in bulk soils and bedrock, were found. On the investigated dam, anomalies of the electrical conductivity and the frequency dispersion coincide with anomalies of the self-potential. This indicates increased filtration. Thus, the use of the remote induction soundings and the frequency dispersion methods together with widely applied VES and SP methods enhances the reliability of research and provides additional information about the hydrogeological situation in the area of the dam.
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-020-0114-1
       
  • Alternative formulae for robust Weighted Total Least-Squares solutions for
           Errors-In-Variables models

    • Free pre-print version: Loading...

      Abstract: Abstract Weighted Total Least-Squares (WTLS) can optimally solve the issue of parameter estimation in the Errors-In-Variables (EIV) model; however, this method is relatively sensitive to outliers that may exist in the observation vector and/or the coefficient matrix. Hence, an attempt to identify/suppress those outliers is in progress and will ultimately lead to a novel robust estimation procedure similar to the one used in the Gauss-Markov model. The method can be considered as a follow-up to the WTLS solution formulated with the standard Least-Squares framework. We utilize the standardized total residuals to construct the equivalent weights, and apply the median method to obtain a robust estimator of the variance to provide good robustness in the observation and structure spaces. Moreover, a preliminary analysis for the robustness of related estimators within the EIV model is conducted, which shows that the redescending M-estimates are more robust than the monotonic ones. Finally, the efficacy of the proposed algorithm is demonstrated through two applications, i.e. 2D affine transformation and linear regression on simulated data and on real data with some assumptions. Unfortunately, the proposed algorithm may not be reliable for detecting multiple outliers. Therefore, MM-estimates within the EIV model need to be investigated in further research.
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-019-0282-z
       
  • Comparison of three methods for computing the gravitational attraction of
           tesseroids at satellite altitude

    • Free pre-print version: Loading...

      Abstract: Abstract Global gravity modelling is one of the most important issues in geophysics and geodesy. Because a tesseroid model comprises the curvature of the Earth, the computation methods for the gravitational potential of tesseroids and its first-order derivatives in spherical coordinates are attracting great attention in recent years. In this paper we deal with the numerical evaluation of the radial component of the gravitational attraction generated by tesseroid masses at satellite height with the Gauss-Legendre quadrature (GLQ), the Taylor series expansion (TSE) and the prism approximation (PA) methods. Forward modelling of tesseroids of 1° × 1° and 5′ × 5′ are performed by three computation methods and the comparison between them are made in terms of computational efficiency and accuracy. The numerical results show that the GLQ of order 5 can provide the adequate accuracy for the gravity modelling of 1° × 1° tesseroids at satellite height. The GLQ of order 2 and TSE methods are superior to the PA approach in both computational accuracy and efficiency. The satellite height has important impact on the accuracy of the GLQ and TSE, whereas it has no effect on the PA method. In addition, we developed combined GLQ approach and combined TSE method, respectively, for global gravity modelling based on 1° × 1° and 5′ × 5′ tesseroids. Apart from the synthetic tesseroids, 1° × 1° data from the CRUST1.0 global crustal model and 5′ × 5′ rock-equivalent topographic data from the Earth2014 model are used to validate two combined methods. The numerical results show that these two combined methods can balance the computational accuracy and efficiency.
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-020-0149-3
       
  • An alternative geoid model for Africa using the shallow-layer method

    • Free pre-print version: Loading...

      Abstract: Abstract The aim of the current investigation is to determine an alternative geoid model for Africa using the shallow-layer method. The shallow-layer method, following the basic definition of the geoid, differs essentially from the traditional geoid determination techniques (Stokes and Molodensky) that it doesn’t need real gravity data. It comes from the definition of the geoid. Here, the shallow-layer method is used to determine a 5′ × 5′ geoid model for Africa covering the latitudes between −36°N and 39°N and longitudes from −20°E to 53°E The Earth Gravitational Model (EGM2008), the global topographic model (DTM2006.0), the global crustal model (CRUST1.0) and the Danish National Space Center data set (DNSC08) global models have been used to construct and define the shallow layer and its interior structure. A combination of prism and tesseroid modelling methods have been utilized to determine the gravitational potential produced by the shallow-layer masses. The validation and tests of the computed shallow-layer geoid have been done at two different levels. First, a comparison between the computed shallow-layer geoid and the recently developed AFRgeo2019 gravimetric geoid for Africa (based on real gravity data) has been carried out. Second, a comparison of the computed shallow-layer geoid with several geoid models computed using different global geopotential models has been performed. The results show that the computed shallow-layer geoid behaves similarly to those determined by the global geopotential models. Differences between the shallow-layer and the AFRgeo2019 gravimetric geoids are generally small (below 0.5 m) at most of the African continent
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-020-0301-0
       
  • Two-dimensional magnetotelluric data inversion using Lanczos
           bidiagonalization method with active constraint balancing

    • Free pre-print version: Loading...

      Abstract: Abstract The magnetotelluric (MT) technique is an electromagnetic geophysical method, which is widely used as a complementary to seismic surveys for exploration of hydrocarbon reservoirs. In the inversion process, the method of matrix inverse calculation has a considerable effect on the speed of the inversion and the quality of obtained models. Lanczos Bidiagonalization (LB) method has been reported to be a fast and efficient approach for solving the inversion problems. In this study, we employ LB method for inverting large-scale 2D MT data. In LB algorithm, the full set of equations is replaced by a dimensionally reduced system of equations. As a result, the speed of the solution procedure is increased, while the original problem is solved with a high accuracy. In addition, we employ active constraint balancing approach for determining the optimum regularization parameter. The advantage of the method is that for highly resolvable parameters, a small value of the Lagrangian multiplier is assigned, and vice versa. The results of the synthetic data inversion show that both methods require equal computer memory but LB method is faster and more reliable than conjugate gradient method. The proposed approach is also applied to inverse real MT data collected from the Kashan area. The Kashan area is the most interesting area for oil and gas exploration of the Central Iran Basin. The inversion results obtained by LB are in a good agreement with the geological structure of the study area and the drilling data.
      PubDate: 2021-04-01
      DOI: 10.1007/s11200-020-0150-x
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 44.201.96.43
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-